Endoscopes are well-known optical imaging devices used for viewing objects within cavities or the internal surfaces of cavities, with additional capabilities of providing channels for insertion of devices to act upon or treat conditions of interest found. While the herein described invention has application in many fields, it has particular relevance to the medical field wherein flexible endoscopes are employed to view and treat deep and convoluted passages of the human body.
In a typical endoscope designed for such purposes, the distal tip of the instrument is made maneuverable by employing two or more angularly spaced cables which interact mechanically with a series of vertebrated or specifically profiled rings located adjacent to the distal end of the instrument. Bending and deflection of the rings is obtained by tensioning and relaxing the cables in accordance with controls located at the proximal end of the endoscope on the control head. The means for applying tension and relaxing forces to these cables have been the subject of extensive technological effort resulting in controls such as joysticks or coaxial control wheels found on many well-known endoscopes. The object of these efforts has been to provide on the control head of the endoscope cable tensioning and relaxing means accessible and comfortable to the hands and fingers of the operator, and, consistent with holding the scope, operating all other controls, and allowing such other manipulations of the endoscope (i.e., torque, pushing and pulling) as are deemed effective for the clinical procedure for which the endoscope was designed.
Throughout this disclosure, it will be appreciated that the term "cable" is intended to refer to any elongate material which can be effectively utilized to operatively connect the distal end of the instrument to the control head. Thus, for purposes of the invention, wire, bands, chains and the like are considered to be equivalent to cables.
In the practice of medicine, a common form of such a device is used for inspection of the human ureter while a similarly structured device is used for inspection of the urethra and bladder. The endoscope is conventionally used in the diagnosis of tumors and other conditions in the urinary tract. The endoscopic examination involves the physician observing the urinary or vesical wall through an eyepiece in the control head of the instrument. Generally, the endoscope is provided with a source of illumination at its objective end, the end which is placed adjacent the area to be examined, and a bundle of light-transmitting fibers through which an image of the examined area is transmitted back to the eyepiece. The endoscope can further incorporate a channel which provides a washing fluid for application to the site under examination as well as a surgical tip and other features.
A factor to be considered in the construction of the endoscope for its normal medical use is its flexibility and articulation which permits the objective tip to be directed along the urinary tract. An endoscope can be made to traverse a considerable distance within this tract providing that any bends in the channel have a sufficiently large radius of curvature to enable the objective end of the endoscope to be readily articulated to follow the course of the tract. Care must be taken, however, to precisely guide the instrument so as not to puncture the vesical wall, especially as the device is being inserted.
The jet engine is one type of mechanical structure for which elongated tubular inpection devices, particularly such devices incorporating flexible fiber optics, have been found to be most useful, particularly to inspect the first stage, or high temperature stage, of the engine just behind the burner can which has components that are most subject to wear and deterioration. The arrangement of the jet engine's rotor and stator blades, particularly those in the high temperature stage of the engine, presents a most complex geometry which has not been amenable to inspection in the past other than by first disassembling the engine. There had previously been a need for some form of inspection device which could be placed near the rotor and stator blades, and other important sites within the engine, for the inspection thereof without the laborious task of disabling the engine. The use of this type of instrument has effected substantial savings in the cost of maintenance of the engines. Savings have resulted from the reduced man-hours achieved by avoiding the disassembly and reassembly of the engine. Additional savings have resulted from the increase in service time of the engine since the downtime for maintenance has been substantially reduced.
While the state of the art relating to endoscopes is relatively advanced today, there are still recurring problems which result when excessive stresses are applied to the operating cables by the hand operated control mechanism. In an extreme situation, this can result in breakage of the cable or, in a less extreme situation, to permanently stretching the cable. In the former instance, the endoscope is rendered useless until the cable has been replaced. In a latter instance, the endoscope loses a portion of its original deflection capability, making it necessary to take up the slack of the stretched cable and recalibrate the instrument. In both instances, it is necessary to open the instrument, usually at the factory or at a well equipped service center, and perform the necessary operations to return the instrument to its former operating condition. This procedure, of course, results in considerable downtime thereby creating scheduling problems, possibly delaying for long periods of time critical inspection procedures which cannot be performed until the instrument has been repaired. This, of course, causes substantial frustration to the user and is economically detrimental.